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Switch traffic problem....

we have a couple of 3Com SuperStack 3 switches that all of the hosts in our network are plugged into.
I just went onto the web interface today and there seems to be a lot of warnings and critical events there concerning the ports of the switch.
It will go from port to port of the switch and if there is something plugged into the port that is transfering a file or RIS image, etc., it will say that there has been a communication problem. If you click on 'retry' it will go through after that.

I've been playing around with the port speeds to try things like 10, 100, etc., instead of the auto, but nothing really seems to help.

Has anyone run into something like this, and if so, is there a way to cure this kind of problem?
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wlandymore
Asked:
wlandymore
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2 Solutions
 
rburns50Commented:
This could be caused by many things- switch failure, virus traffic on the LAN, another device on the LAN setup as a bridge and responding to arps for everyone's IP address, etc. Did the switches ever run clean? Does one port seem to have more errors than others?

I've found that the first step is always to reload the switch. Sometimes arp caches get full and a reset/rediscovery is the best medicine- it doesn't always make sense, but fixes 50% of the problems.

If that doesn't help, look at the port stats and see if any of them have error counts growing faster than the others, or have more utilization than the others etc- stuff that stands out. If there is a port like that, unplug that PC from the switch and see if the probems go away. If so, you have the smoking gun- you'll then need to troubleshoot if it's the PC or the cabling or the switch port by trying different combinations.
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wlandymoreAuthor Commented:
Yeah, I tried reloading the switch but that didn't seem to help. I noticed this because I had made an image for a RIS server with riprep and I was trying to upload it to the server. This worked before but now it will give me an error that it can't find the file, but if I click 'retry' it will find it and move on. It's taken me two days of clicking retry and I still haven't got it to the RIS server.
I tried plugging only those two machines into a hub but that didn't improve anything either.

The error messages I'm getting are from the switch addresses.

Trap:Link is unavailable on unit 1, port 24
Trap:Link is unavailable on unit 1, port 12
Trap:Link is unavailable on unit 1, port 11
Trap:Link is unavailable on unit 1, port 24
Section of network is down
Trap:Link is unavailable on unit 1, port 12
Trap:Link is unavailable on unit 1, port 11

Even though it seems to repeat those ports there in sequence, I tried to unplug everything from the bottom switch except for the RIS server and the Image computer, then reload the switch and try it again, but it didn't help.
I also tried taking everything out of those ports in the switch and that didn't make any difference either.
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rburns50Commented:
Dumb question, but have you considered that the NIC is maybe bad in one or both of those hosts? If they still didn't work on a shared hub, you have eliminated the switch as being the problem. Easiest thing to try first would be the cabling- replace the Cat5 cable for each. If no joy, try swapping out the NIC's.
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wlandymoreAuthor Commented:
yeah, I tried the cabling but I haven't done the NIC's yet. I can't shut them down yet because I don't want to lose the RIS image install. As painful as this process is, I think I'm almost done with it so I'll try to gut it out and see if I can salvage the install.
Then I'll try swaping out the cards....I'll let you know how it goes.
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rburns50Commented:
Cool...good luck. I remember the days of "sneaker net"...another option is a crossover cable between the two hosts (as long as they have static IP's).
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wlandymoreAuthor Commented:
it probably can't be the NIC of the image machine because I tried a riprep from another machine and I got the same behavior. However, it could be the NIC of the RIS server because that would be common in both cases...
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pseudocyberCommented:
You'll have to read your documentation, but some switches will disable ports automatically when they see excessive errors.  You said you were playing around with settings ...

IMHO, your servers, and their switch ports, should be manually set to 100 Mbps Full Duplex.  You MUST set the NIC on the other end of the cable to be the same.  If one side is 100 Full and the other side is Auto, the Auto side will set itself to half duplex causing LOTS of errors - especially if there's high traffic levels ... like say in an image restore.
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wlandymoreAuthor Commented:
The points go to rburns50....

I decided to give up on pressing 'retry' on the riprep every 2 minutes and just replace the NIC cards in both machines and then start again.
I set riprep up and left it to go overnight. When I came back in the machine was shut off like it should be and the image was on the RIS.

I still have to take a look at why the switch is having a problem, but the only network trouble we noticed was with the RIS so now that it's solved I have a lot more space. The actual users haven't complained about any slowness of inactivity.

I just can't believe this was all caused by a failed NIC. Usually when a NIC fails on me I just see it stop working totally, not intermittently.

thanks for the help.
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wlandymoreAuthor Commented:
I upped the point value and gave 200 points to rburns50 (because it was his comment that fixed it) and 50 points to you pseudocyber, because it was originally thought to be a switch problem.

Your comment has also given me some good things to think about on route to solving the switch errors.

thanks
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pseudocyberCommented:
You're welcome.  Glad I could help. :)
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rburns50Commented:
Nice to see a happy ending- thanks for the points.
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